Antibodies are widely used for diagnostic and research purposes for localizing an antigen within a cell, tissue, or other biological sample. For histopathology or cytology, cells are usually first exposed to a primary antibody which is specific for the desired target antigen but not directly detectable. In a subsequent step, the primary antibody is detected with a labeled secondary antibody which recognizes the primary antibody. This procedure is somewhat cumbersome and may result in undesirable background staining due to non-specific reactivity of the secondary antibody. In addition, in order to visualize two or more antigens, the primary antibodies must be from two different species such that each secondary antibody is not cross-reactive; expensive species-specific secondary antibodies must therefore be used for each primary antibody. With advances in optical and digital imaging and detection, multiply-labeled samples and simultaneous detection of several analytes is possible, yet the aforementioned biological limitations do not permit full advantage to be taken of these advances. Moreover, since 99 monoclonal antibodies are generated typically only in mice and rats, in conventional dual or triple labeling, only one antibody can be monoclonal. This can be an important restriction.
Several techniques are available to circumvent these limitations, including direct chemical conjugation of the primary antibody with a detectable molecule, or direct conjugation with biotin and subsequence detection with a fluorescent avidin. These procedures are cumbersome and requires purification of the primary antibodies.
It is towards the facile preparation of a detectable primary antibody to any desired antigen that the present invention is directed.
The citation of any reference herein should not be construed as an admission that such reference is available as “Prior Art” to the instant application.